一种新型近β型Ti-5.5Mo-6V-7Cr-4Al-2Sn-1Fe合金热变形行为  

Hot deformation behavior of new type of near β type Ti-5.5Mo-6V-7Cr-4Al-2Sn-1Fe alloy

作　　者：周强 程军[2,3] 于振涛 崔文芳[1] ZHOU Qiang;CHENG Jun;YU Zhen-tao;CUI Wen-fang(Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education),Northeast University,Shenyang 110004,China;Shaanxi Key Laboratory of Biomedical Metal Materials,Northwest Institute for Non-ferrous Metal Research,Xi’an 710016,China;State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]东北大学材料各向异性与织构教育部重点实验室,沈阳110004 [2]西北有色金属研究院陕西省医用金属材料重点实验室,西安710016 [3]西北工业大学凝固技术国家重点实验室,西安710072

出　　处：《材料工程》2019年第6期121-128,共8页Journal of Materials Engineering

基　　金：国家重点研发项目计划(2016YFC11020003);陕西省重点研发计划项目(2017ZDXM-SF-039);陕西省重点科技创新团队项目(2016KCT-30)

摘　　要：采用Gleeble-3800型热模拟试验机对一种新型近β型Ti-5.5Mo-6V-7Cr-4Al-2Sn-1Fe(质量分数/%)钛合金进行等温恒应变速率压缩实验。变形温度范围为:655~855℃,应变速率范围为:0.001~10s^-1 ,最大真应变为0.8。根据实验数据,建立了该合金的高温流变应力模型,计算出热变形激活能约为255kJ/mol,并绘制出热加工图。结合热加工图与材料的显微组织分析可知,在高应变速率(1~10s^-1 )条件下变形时,在热加工图上表现为材料的功率耗散值(η)低,为失稳区域,易产生绝热剪切带与局部塑性流动、开裂等现象。在应变速率小于0.01s^-1 和相变点( T β)温度以下(655~755℃)进行热变形时,组织变化主要以动态回复为主;在应变速率小于0.01s^-1 和 T β以上(755~855℃)进行热变形时,组织发生动态再结晶,且随着温度的升高,新产生的再结晶晶粒逐渐长大。在相变点附近(755~770℃),变形速率为0.001~0.003s^-1 区域内变形时,功率耗散值达到最大值,组织发生动态再结晶,该区域为合金热变形的“安全区”。The isothermal constant strain rate compression tests of Ti-5.5Mo-6V-7Cr-4Al-2Sn-1Fe alloy were conducted by Gleeble-3800 simulator. The hot deformation temperature range is from 655℃ to 855℃ and the strain rate range is from 0.001s^-1 to 10s^-1 and the maximum true strain is 0.8. A high temperature flow stress model was built with activation energy of 255kJ/mol according to the experimental results for the alloy and the processing map of alloy was constructed according to DMM model. The metallographic analysis of alloy shows that the alloy exhibits domain of flow localization and adiabatic shear bands and low power dissipation efficiency in the high strain rate(1-10s ^-1 ). The alloy undergoes dynamic recovery in the temperature region of 655-755℃ and the strain rate below 0.01s ^-1 . The dynamic recrystallization takes place at the strain rate below 0.01s^-1 and in the temperature region of 755-855℃, the original deformed grains and recrystallized grains gradually grow with the increase of temperature. When the temperature is 755-770℃ and the strain rate is 0.001-0.003s^-1 , the alloy’s power dissipation efficiency reaches the maximum and the recrystallized grain is uniform and fine. These regions can be considered as the optimal parameter range of isothermal compression for the alloy.

关 键 词：钛合金 热变形 流变应力模型 热加工图 流变失稳 

分 类 号：TG146.23[一般工业技术—材料科学与工程]